1. Field of the Invention
This invention relates generally to the production of interesting optical effects by grooves formed in a light reflecting surface, and more specifically, this invention relates to a method and apparatus for mass producing light reflecting surfaces having grooved surfaces.
2. Description of the Prior Art
It is known that various interesting and pleasing optical effects can be achieved by placing grooves or lines in a reflecting surface, such as a metallic foil. An example of a use of these optical effects may be found in certain handmade greeting cards.
While the effects achieved with such reticulated prior art arrangements can be quite impressive, they have been limited in applicability because of the inability to mass produce such grooves surfaces. Previous attempts to hot stamp metallic foil or other light reflecting surfaces in web printing have not been very successful.
Since there are many uses for the optical effects that may be achieved with lined surfaces of this type, a process by which such items could be mass produced, such as by using a web type press, would be most beneficial. The limited number of such items which can be hand or individually produced is economically unfeasible for many applications which would be feasible with a web type press production method.
The present invention provides a method of mass producing reticulated devices that have desirable optical effects. In accordance with this invention, a hand or computer generated engraving is first made in a relatively soft deformable metal foil which is secured to a more rigid substrate, with an intervening deformable material therebetween, which together form a laminated structure. Using suitable hand engraving tools, having engraving edges of varying sizes and shapes, a hand engraved design is formed in the metal foil. An engraved design may also be generated by a computer and engraved by computer controlled engraving tools. The design is typically formed by making a plurality of parallel depressions in the foil. The parallel depressions are made of varying depths and widths by the use of various tools, and by manipulating each of the tools, such as by rotating and by applying variable pressures to the tools. In forming the parallel depressions of varying widths and depths, the metal foil is depressed into the deformable material, which retains the shape of the parallel depressions formed in the metal foil, and provides backup support to the deformed foil.
The laminated structure, with an engraved design formed therein, is placed in a metal plating bath, in a plating tank, to form a relatively hard metal coating over the engraved soft deformable metal foil. The laminated structure is maintained in the metal plating bath for a sufficient length of time to form a hard metal coating on the soft metal foil, which coating is of sufficient strength to be used as a die which is in the form of a mirror image of the grooves first formed in the soft deformable metal foil. The die may then be used to form grooves, corresponding to those first engraved in the soft deformable metal foil, in a metal foil, a metallized Mylar foil, or similar material which is capable of being deformed to the shape of the hand or computer controlled engraved grooves.
Upon being removed from the metal plating bath, the laminated structure, and more particularly the soft metal foil, is separated from the hard metal coating. The hard metal coating thus forms a hard metal plate having a mirror image of the engraved design therein. While the metal plate is hard in the sense of retaining the engraved surface thereon, it is also, in its entirety, somewhat flexible. That is, while it is generally formed as a flat surface, it can be resiliently bend into a curved form. One side of a substrate, which has an adhesive on both sides, is secured to the back side of the hard metal plate which was separated from the soft metal foil. The hard metal plate is then secured to the drum of a web type printer by the adhesive on the second side of the substrate. With the hard metal plate secured to the web printer drum, the web printer may be used to apply the originally hand or computer formed engraving, to a material engaged by the hard metal plate on the drum, as it is passed through the web type printer.
One of the preferred metals for use in the metal plating bath to form the hard metal coating is a compound containing a significant amount of nickel and also iron. However, other metals having similar desirable characteristics may also be used. Typically, of the materials to which the engraving may be imparted are metal foils, metallized Mylar, and other highly reflective materials.